/*
 * HeapSort.java
 *
 * Copyright (C) 2002-2006 Alexei Drummond and Andrew Rambaut
 *
 * This file is part of BEAST.
 * See the NOTICE file distributed with this work for additional
 * information regarding copyright ownership and licensing.
 *
 * BEAST is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 *  BEAST is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with BEAST; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA  02110-1301  USA
 */

package dr.util;

import dr.math.MathUtils;

import java.util.AbstractList;
import java.util.Comparator;
import java.util.Vector;

/**
 * sorts numbers and comparable objects by treating contents of array as a binary tree.
 * KNOWN BUGS: There is a horrible amount of code duplication here!
 *
 * @version $Id: HeapSort.java,v 1.7 2006/02/20 17:36:23 rambaut Exp $
 *
 * @author Alexei Drummond
 * @author Korbinian Strimmer
 */
public class HeapSort {
	
	//
	// Public stuff
	//

	/**
	 * Sorts an array of indices to vector of comparable objects 
	 * into increasing order.
	 */
	public static void sort(AbstractList array, int[] indices) {
	
		// ensures we are starting with valid indices
		for (int i = 0; i < indices.length; i++) {
			indices[i] = i;
		}
	
		int temp;
		int j, n = array.size();
		
		// turn input array into a heap
		for (j = n/2; j > 0; j--) {
			adjust(array, indices, j, n);
		}

		// remove largest elements and put them at the end
		// of the unsorted region until you are finished
		for (j = n-1; j > 0; j--) {
			temp = indices[0];
			indices[0] = indices[j];
			indices[j] = temp;
			adjust(array, indices, 1, j);
		}
	}	

	/**
	 * Sorts a vector of comparable objects into increasing order.
	 */
	public static void sort(AbstractList array) {
	
		Object temp;
		int j, n = array.size();
		
		// turn input array into a heap
		for (j = n/2; j > 0; j--) {
			adjust(array, j, n);
		}

		// remove largest elements and put them at the end
		// of the unsorted region until you are finished
		for (j = n-1; j > 0; j--) {
			temp = array.get(0);
			array.set(0, array.get(j));
			array.set(j, temp);
			adjust(array, 1, j);
		}
	}	

	/**
	 * Sorts an array of comparable objects into increasing order.
	 */
	public static void sort(Comparable[] array) {
	
		Comparable temp;
		int j, n = array.length;
		
		// turn input array into a heap
		for (j = n/2; j > 0; j--) {
			adjust(array, j, n);
		}

		// remove largest elements and put them at the end
		// of the unsorted region until you are finished
		for (j = n-1; j > 0; j--) {
			temp = array[0];
			array[0] = array[j];
			array[j] = temp;
			adjust(array, 1, j);
		}
	}

	/**
	 * Sorts an array of objects into increasing order given a comparator.
	 */
	public static void sort(Object[] array, Comparator c) {
	
		Object temp;
		int j, n = array.length;
		
		// turn input array into a heap
		for (j = n/2; j > 0; j--) {
			adjust(array, c, j, n);
		}

		// remove largest elements and put them at the end
		// of the unsorted region until you are finished
		for (j = n-1; j > 0; j--) {
			temp = array[0];
			array[0] = array[j];
			array[j] = temp;
			adjust(array, c, 1, j);
		}
	}	

	/**
	 * Sorts an array of doubles into increasing order.
	 */
	public static void sort(double[] array) {
	
		double temp;
		int j, n = array.length;
		
		// turn input array into a heap
		for (j = n/2; j > 0; j--) {
			adjust(array, j, n);
		}

		// remove largest elements and put them at the end
		// of the unsorted region until you are finished
		for (j = n-1; j > 0; j--) {
			temp = array[0];
			array[0] = array[j];
			array[j] = temp;
			adjust(array, 1, j);
		}
	}

	/**
	 * Sorts an array of doubles into increasing order, ingoring sign.
	 */
	public static void sortAbs(double[] array) {

		double temp;
		int j, n = array.length;

		// turn input array into a heap
		for (j = n/2; j > 0; j--) {
			adjustAbs(array, j, n);
		}

		// remove largest elements and put them at the end
		// of the unsorted region until you are finished
		for (j = n-1; j > 0; j--) {
			temp = array[0];
			array[0] = array[j];
			array[j] = temp;
			adjustAbs(array, 1, j);
		}
	}

	/**
	 * Sorts an array of indices into an array of doubles
	 * into increasing order.
	 */
	public static void sort(double[] array, int[] indices)
	{
	
		// ensures we are starting with valid indices
		for (int i = 0; i < indices.length; i++)
		{
			indices[i] = i;
		}
	
		int temp;
		int j, n = indices.length;
		
		// turn input array into a heap
		for (j = n/2; j > 0; j--) {
			adjust(array, indices, j, n);
		}

		// remove largest elements and put them at the end
		// of the unsorted region until you are finished
		for (j = n-1; j > 0; j--) {
			temp = indices[0];
			indices[0] = indices[j];
			indices[j] = temp;
			adjust(array, indices, 1, j);
		}
	}


	/** test harness for heapsort algorithm */
	public static void main(String[] args) {

		int testSize = 100;

		// test array of Comparable objects
		
		ComparableDouble[] test = new ComparableDouble[testSize];
		
		for (int i = 0; i < test.length; i++) {
			test[i] = new ComparableDouble(MathUtils.nextInt(testSize * 10));
		}

		sort(test);
		for (int i = 0; i < test.length; i++) {
			System.out.print(test[i] + " ");
		}
		System.out.println();

		// test index to Vector of Comparable objects
		
		Vector testv = new Vector();
		int[] indices = new int[testSize];
		
		for (int i = 0; i < testSize; i++) {
			testv.addElement(new ComparableDouble(MathUtils.nextInt(testSize * 10)));
		}

		sort(testv, indices);
		for (int i = 0; i < test.length; i++) {
			System.out.print(testv.elementAt(indices[i]) + " ");
		}
		System.out.println();
		
		
		// test index to array of doubles
		
		double[] testd = new double[testSize];
		//int[] indices = new int[testSize];
		
		for (int i = 0; i < testSize; i++)
		{
			testd[i] = MathUtils.nextInt(testSize * 10);
		}

		sort(testd, indices);
		for (int i = 0; i < test.length; i++)
		{
			System.out.print(testd[indices[i]] + " ");
		}
		System.out.println();

	}

	// PRIVATE STUFF

	/**
	 * helps sort an array of indices into a vector of comparable objects.
	 * Assumes that array[lower+1] through to array[upper] is
	 * already in heap form and then puts array[lower] to
	 * array[upper] in heap form.
	 */
	private static void adjust(AbstractList array, int[] indices, int lower, int upper) {
	
		int j, k;
		int temp;
		
		j = lower;
		k = lower * 2;

		while (k <= upper) {
			if ((k < upper) && (((Comparable)array.get(indices[k-1])).compareTo(array.get(indices[k])) < 0)) {
				k += 1;
			}
			if (((Comparable)array.get(indices[j-1])).compareTo(array.get(indices[k-1])) < 0) {
				temp = indices[j-1];
				indices[j-1] = indices[k-1];
				indices[k-1] = temp;
			}
			j = k;
			k *= 2;
		}
	} 

	/**
	 * helps sort an vector of comparable objects.
	 * Assumes that array[lower+1] through to array[upper] is
	 * already in heap form and then puts array[lower] to
	 * array[upper] in heap form.
	 */
	private static void adjust(AbstractList array, int lower, int upper) {
	
		int j, k;
		Object temp;
		
		j = lower;
		k = lower * 2;

		while (k <= upper) {
			if ((k < upper) && (((Comparable)array.get(k-1)).compareTo(array.get(k)) < 0)) {
				k += 1;
			}
			if (((Comparable)array.get(j-1)).compareTo(array.get(k-1)) < 0) {
				temp = array.get(j-1);
				array.set(j-1, array.get(k-1));
				array.set(k-1, temp);
			}
			j = k;
			k *= 2;
		}
	} 

	/**
	 * Assumes that array[lower+1] through to array[upper] is
	 * already in heap form and then puts array[lower] to
	 * array[upper] in heap form.
	 */
	private static void adjust(Comparable[] array, int lower, int upper) {
	
		int j, k;
		Comparable temp;
		
		j = lower;
		k = lower * 2;

		while (k <= upper) {
			if ((k < upper) && (array[k-1].compareTo(array[k]) < 0)) {
				k += 1;
			}
			if (array[j-1].compareTo(array[k-1]) < 0) {
				temp = array[j-1];
				array[j-1] = array[k-1];
				array[k-1] = temp;
			}
			j = k;
			k *= 2;
		}
	}

	/**
	 * Assumes that array[lower+1] through to array[upper] is
	 * already in heap form and then puts array[lower] to
	 * array[upper] in heap form.
	 */
	private static void adjust(Object[] array, Comparator c, int lower, int upper) {
	
		int j, k;
		Object temp;
		
		j = lower;
		k = lower * 2;

		while (k <= upper) {
			if ((k < upper) && (c.compare(array[k-1], array[k]) < 0)) {
				k += 1;
			}
			if (c.compare(array[j-1], array[k-1]) < 0) {
				temp = array[j-1];
				array[j-1] = array[k-1];
				array[k-1] = temp;
			}
			j = k;
			k *= 2;
		}
	}

	/**
	 * helps sort an array of doubles.
	 * Assumes that array[lower+1] through to array[upper] is
	 * already in heap form and then puts array[lower] to
	 * array[upper] in heap form.
	 */
	private static void adjust(double[] array, int lower, int upper) {
	
		int j, k;
		double temp;
		
		j = lower;
		k = lower * 2;

		while (k <= upper) {
			if ((k < upper) && (array[k-1] < array[k])) {
				k += 1;
			}
			if (array[j-1] < array[k-1]) {
				temp = array[j-1];
				array[j-1] = array[k-1];
				array[k-1] = temp;
			}
			j = k;
			k *= 2;
		}
	} 
/**
	 * helps sort an array of doubles.
	 * Assumes that array[lower+1] through to array[upper] is
	 * already in heap form and then puts array[lower] to
	 * array[upper] in heap form.
	 */
	private static void adjustAbs(double[] array, int lower, int upper) {

		int j, k;
		double temp;

		j = lower;
		k = lower * 2;

		while (k <= upper) {
			if ((k < upper) && (Math.abs(array[k-1]) < Math.abs(array[k]))) {
				k += 1;
			}
			if (Math.abs(array[j-1]) < Math.abs(array[k-1])) {
				temp = array[j-1];
				array[j-1] = array[k-1];
				array[k-1] = temp;
			}
			j = k;
			k *= 2;
		}
	}

	/**
	 * helps sort an array of indices into an array of doubles.
	 * Assumes that array[lower+1] through to array[upper] is
	 * already in heap form and then puts array[lower] to
	 * array[upper] in heap form.
	 */
	private static void adjust(double[] array, int[] indices, int lower, int upper) {
	
		int j, k;
		int temp;
		
		j = lower;
		k = lower * 2;

		while (k <= upper)
		{
			if ((k < upper) && (array[indices[k-1]] < array[indices[k]]))
			{
				k += 1;
			}
			if (array[indices[j-1]] < array[indices[k-1]])
			{
				temp = indices[j-1];
				indices[j-1] = indices[k-1];
				indices[k-1] = temp;
			}
			j = k;
			k *= 2;
		}
	} 
}

